1. Field of the Invention
The present invention relates to a broadcast-communication convergence system, and more particularly to a multimedia signal matching system and a method for performing a picture-in-picture function on video signals of various formats.
2. Description of the Related Art
Network convergence describes an integrated networking environment, including voice, video and data transmissions, that has evolved to include integrated services and applications through broadcast and communication networks. Broadcast services through a communication network include TV broadcast services through the Internet, video-on-demand (“VOD”) services offered by existing broadcast stations, and direct satellite broadcasting using communication satellites. Communication services through a broadcast network, on the other hand, include value-added communication services, such as Internet or telephone services, using a cable network. Broadcast-communication convergence is backed up by hardware developments, such as high-speed computer networks, wide-spread deployment of Internet access, and broadband communication networks, as well as by software development, such as digitalization of content with the advent of high definition television (“HDTV”), cable TV, and satellite TV. Thus, current broadcast-communication systems are no longer limited to the simple functions of receiving and displaying broadcast signals, but are now offering broadcast services. Accordingly, broadcast-communication systems, which receive multimedia signals in various formats from converged broadcast-communication networks, must decode the received signals and display the decoded signals.
A variety of transmission technologies have been suggested and developed to provide broadcast and communication convergent services. Multimedia signals (i.e., video and audio signals) are delivered in diverse formats to the users through the broadcast communication network 101. Transmission formats of multimedia signals include an MPEG (Moving Picture Expert Group) format. MPEG is a working group formed to device standards for the encoding both video and audio signals. As a format of broadcast signals, MPEG is divided into a number of formats. To transmit multimedia signals to a communication system, diverse formats for video and audio signals are used.
Picture-in-picture (“PIP”) applications, which serves to display two video signals to display on the same screen simultaneously, can be implemented when two multimedia signals are received from different sources. There is no problem when signals in the same format are received and displayed at the same time. To receive and display video signals in different formats, multiple decoders are required for the PIP application.
FIG. 1 schematically illustrates the receiving end of a conventional digital broadcast communication system. As shown, the conventional receiving end of, a digital broadcast communication network 101, contains set-top boxes 103 and 107 for receiving broadcast communication signals from the broadcast communication network 101 and user display devices 105 and 109.
Set-top boxes 103 and 107 include multiple decoders to decode multimedia signals received in different formats. These set-top boxes 103 and 107 convert signals received from multiple channels into binary signals through a demodulator. The binary signals are divided into audio, video, and data signals and decoded by a demultiplexer. The set-top boxes 103 and 107 convert the received signals into signals displayable on the display devices 105 and 109.
As stated earlier, to perform a PIP function on video signals in various formats in conventional broadcast-communications networks requires set-top boxes 103 and 107 to include additional decoders in order to decode each multimedia format. If two or more set-top boxes are used in a home, there will be no problem in receiving multimedia signals in one and the same format. However, multimedia signals in various formats can only be displayed in a PIP mode when each set-top box has multiple decoders for decoding the various formats. Unless such multiple decoders are provided, the PIP function cannot be implemented.